The Dodge Challenger Message Board

HI - i have set up my 360 to ground run in the garage at home (see pic). It was running fine with the points system but then i changed over to a rebuilt electronic dizzy, new Orange ECU and MSD Blaster2 coil. Now it won't run. It backfires up through the carby all the time and the ballast resister (1.25ohm that came with the Blaster coil) gets very hot very quick and starts crackling and smoking after about 15 secs. Unfortunately it won't run for me to check the timing. I have made sure the system is wired up correctly.
As teh cam is less than mild i have closed up all the vacuum ports, no vacuum advance yet and no PCV- all closed, to give max vacuum.

However i noticed that the elec dizzy rotor position compared to the points dizzy rotor position is slightly turned more clockwise- ie, it is a few degrees further on. BUt this shouldn't matter as its all relative to the dizzy housing. Should the ballast get this hot so quick when ignition is first turned on? I have tried various initial timing settings- always just backfires after firing and dies. I have another new dizzy and used ECU- i might start swapping things around to eliminate.

So you have changed nothing at all since you ran the points system? No cam change or changes to the vacuum lines etc?

I will assume so.

New resistors always smoke when new so don't worry too much about that at this point. It should settle down.

It sounds to me as if the timing is way out. Either 180 degrees out or the rotor is indexed differently to your old distributor.

Make sure you are at TDC on the compression stroke when you line the rotor up with #1 on the dissy cap.
Rotate the engine so that you see the exhaust valve open and close. The next time the timing mark comes around is TDC firing.

I have a detailed instructional thread on here on how to time the engine. it might be in the engine section though.

Ta Dave, yes, nothing changed at all except the ignition (and blocking the PCV of course). I did read through your Ignition timing part- very good grounding info. I thought at first it was 180 out, although i was careful to put the elec dizzy in the same as the points one. But i rotated it 180 as i momentarily got confused and boy did it backfire then! So it's not that. My method for determning the correct TDC is to remove a plug and put light finger pressure over the spark plug hole while you are clicking the engine over with a remote starter (essential item!). You can feel the whoosh of air on the comp stroke as the timing marks come around. This method saves taking off the rocker cover.

Thanks for ballast advice- its rather disconcerting seeing smoke coming off the thing.

I'm sure its timing. i'll go back and get it running again with the points and start again. If youdon't hear from me again it means there's probably been an explosion.

Yes I used to check with my finger on the spark plug hole too.

But I don't any more as on some engines there is a little pressure also on the exaust stroke (not as much) but I have been mislead before.

I much rather make 100% sure by watching the valves. I also drill a small hole in the dizzy cap in line with the #1 plug lead post so I can see for sure that the rotor is just coming up to the correct post.

Doing it that way i am always 100% sure in my mind I have it right. Then if there are problems starting I have fewer things to double check.

Dave, that's a great idea about drilling the sight hole in the dizzy cap. It could be plugged with a grommet to stop dirt getting in there normally.

Anyway, Success! I got it purring- well as good as it will idle with a 296 duration. All it was, was the one wire connected from the coil + and ballast that goes to the START position on starter motor or starter relay.

This is in order to supply a full 12V to the coil on start up and drops off after engine starts. I followed the Flintstone diagram attached and its the yellow wire i'm talking about, but in my case it did not like it! I did not have that wire connected with the points. But when i put the points dizzy back i left it there and it ran but only just. Like it was on 4 cylinders, or very weak spark or something, Absolutely no response to throttle. As soon as i removed the wire it ran properly, for both points and ECU ign. I also noticed that with this wire there the starter motor would try to work occasionally when the ignition was turned on- indicating that there was current getting through the ballast- THAT WAS why the ballast was getting so hot!

So not sure how they wire that in the cars, will have to sus out one.

Anyway, that's all it was- a huge current drain causing the coil to not work properly.

The hole I drill is only a couple of mm diameter. No worries about dirt getting in. You don't let your engine get dirty anyway do you?

I see what you mean. i had imagined a larger hole on the vertical wall of the cap to be seen from the front. No i try to keep my engines as clean as reasonably possible but the engine is an inherently dirt-accumulating area- there is constant flow through from the front area to dust outside and up underneath, its close to the road and the dizzy has small amounts of grease inside so no matter how clean it looks on the outside, stuff will find its way in eventually into the most inner and secret crevices known to mortal men.

Dirt roads eh?

Something I never have to worry about here.

The cap should be vented though. If it has a vent - same issue. If it does not have a vent - you need one because ozone build-up in the cap causes spark scatter (ozone conducts).

But if dirt is finding its way in then a small blob of silicon will seal it.

now i know what i did wrong- my half brain was not working that day. That wire to the start position is correct- so that the coil gets a full 12V on start up- but it has to go through the START switch first. i had it permanently connected to the start terminal on the starter motor. It has to go through the switch (in my case a momentary action press button) so that it drops out after start up but also is not causing the drain from the ballast voltage.

Ah!

Oh well. Glad you found it. Is the coil OK? They can get damaged from the heat if connected to full battery voltage for too long.

Pwooorgh- yeah that's another saga! The first time it happened i had the stock 35 year old coil wired in, it may have got hot but was too busy worrying about the rest of it to notice. Then i put in an MSD Blaster2 coil with the ballast it came with (1.25ohm). Then i noticed it! It was red hot- terminals and body etc. Swearing, cursing and moaning, i disconnected it, burning myself in the process and put it in the fridge with soothing apologies. I hope its ok.

Then after wiring it correctly this time, i started playing around with Ohms Law equation (V=IR) to see the voltage drop across the ballast and trying to work out the best ballast resistor value in order to give 9V to the coil. Making it hard was the fact that i am not running an alternator on the engine ground run, so the battery has only got about 11.8V initially during operation, so am trying to work out the current required to run the eng with electronic ignition. I put the batt on charge after each run of 30 minutes. I have put in a 0.5ohm resistor this time- the MSD coil was only getting about 6.8V with the 1.25 ballast with no alternator.